(Reuters Health)

Before scheduling a bikini wax, or shaving down there, consider the results of a new study. Men and women who trimmed or removed their pubic hair were nearly twice as likely to report having had a sexually transmitted infection, or STI, compared with non-groomers, researchers found after adjusting for age and number of sexual partners.

The lesson, according to the study’s senior author, Dr. Benjamin Breyer: "I wouldn’t groom aggressively right before a sexual encounter with a partner I didn’t know well, and I would avoid having sex with an open cut or wound."

Removing pubic hair might tear the skin, opening an entryway for bacteria or viruses, the authors write in the journal Sexually Transmitted Infections.

But in a phone interview, Breyer, a urology professor at the University of California, San Francisco, cautioned that pubic hair grooming also might mask other contributing factors to STIs. Groomers, for example, could be more likely to engage in risky sexual behaviors—behaviors not considered in the study.

It is the first large-scale investigation into the relationship between grooming practices and STIs.

Researchers surveyed 7,470 randomly sampled adults who reported at least one lifetime sexual partner. Some 84 percent of the women and 66 percent of the men groomed their pubic hair.

The 17 percent of groomers who removed all their hair were more than four times as likely to report a history of STIs compared to those who let their hair grow naturally, the study found.

The 22 percent of groomers who trimmed their pubic hair at least weekly reported more than triple the rate of STIs compared to those who left it alone.

U.S. cases of the three most common sexually transmitted infections—chlamydia, gonorrhea and syphilis—reached an all-time high last year, according to the Centers for Disease Control and Prevention.

But Debby Herbenick, a sex researcher and professor at the Indiana University School of Public Health in Bloomington, isn’t ready to advise people to discard their razors on the basis of the study.

"What was really missing from the paper was the aspect of sex," she said in a phone interview. "That’s important because you’re not getting an STI from shaving or trimming your pubic hair."

The only question researchers asked about sex was how many partners participants had in their lifetimes.

"For me, the study isn’t enough to urge anyone to change anything about what they’re doing about the body," said Herbenick, who was not involved with the research.

A previous study found that women who removed all their pubic hair were more likely to engage in casual sexual hookups as opposed to long-term relationships—possible evidence that something other than grooming itself caused the STIs, she said.

Along those lines, in the romantic comedy, "How to be Single," Rebel Wilson playing Robin laments her friend’s LTRP, or "long-term relationship pubes."

Regardless of whether and how people groom their pubic hair, Breyer stressed the importance of practicing safe sex, especially using a condom when engaging in casual sex.

Pornography and Hollywood, particularly a painful-to-watch 2000 episode of HBO’s hit "Sex in the City," with Sarah Jessica Parker playing Carrie Bradshaw getting a Brazilian bikini wax, popularized women stripping their genitals bald, Herbenick said.

The trend appeared to slow during the recession and may be reversing. Earlier this year, Vogue magazine ran a story headlined, "The Full Bush Is the New Brazilian."

But men and women still remove their pubic hair. Because they frequently do so in preparation for sex, Herbenick sees groomers as unlikely to heed Breyer’s advice about waiting to heal after grooming and before having sex.

"We know people are grooming in preparation for sex," she said. "So I don’t think waiting is the answer."

In another recent study in JAMA Dermatology, more than 80 percent of American women said they groomed their pubic hair, and 56 percent reported doing so to get ready for sex. Women groomed regardless of how often they had sex, the gender of their sex partner and their sexual activities.